1. Field of the Invention
The present invention relates to residential buildings and, more particularly, to vents for use in garage walls, garage doors and building foundation walls for buildings and which satisfy federal and international regulations for flood vents and combustion air vents.
2. Description of Related Prior Art
Vents, in the form of louvered panels, have been used in doors, garage doors, garage walls and building walls for ventilation purposes. To prevent intrusion of insects and debris, fine mesh screens have been incorporated with the louvered panels. While these louvered panels and insect screens have met the requirements attendant ventilation of an adjacent enclosed space, it has become increasingly evident that they do not alleviate the pressure buildup due to hydrostatic forces that occur during flooding. A major cause relates to debris clogging the vents which prevents relatively unobstructed flow of water through the vent in either direction. During rising flood waters, the pressure buildup by the water on the exterior surface of a door or wall may be sufficient to collapse the door or wall as there is no equalizing pressure on the other side of the door or wall. As flood waters recede, the enclosure defined in part by a door(s) and walls may enclose a significant depth of water. If the flow of water out of the enclosure is not generally commensurate with the level of the receding flood water external thereto, internal pressures on the door/wall will exist. These flood water related pressures on the exterior and interior surfaces of doors and walls may be sufficient to cause collapse or destruction of the doors and/or walls and may cause the building, or a significant part of it to collapse. Thus, the building may be in effect destroyed rather than just damaged by short term presence of flood waters.
To alleviate flood water related problems and to establish requirements for providing sufficient air for gas fired water heaters and the like that may be present within an enclosed section of a building, numerous national and international regulations have been promulgated.
A national building code (BOCA) (§1210.2) requires ventilation of crawl spaces that provides cross ventilation on at least two approximately opposite sides having openings with a corrosion resistant mesh with not less than one quarter inch (6 mm.), nor more than one half inch (13 mm.) in any direction. The net area of each opening shall be not less than one square foot (0.093 m2) for each 150 square feet (13.95 m2) of foundation space. Additionally, BOCA has certain requirements for buildings and structures erected in areas prone to flooding. More particularly, fully enclosed spaces shall be designed to automatically equalize hydrostatic forces on exterior walls by allowing for entry and exit of flood water. To meet these requirements, there must be at least two openings having a total net area of not less than one square inch (645 mm2) for every square foot (0.1 m2) of enclosed area subject to flooding. The bottom of each opening shall not be higher than 12 inches (305 mm) above grade. The openings, whether equipped with screens, louvers, valves, or other coverings or devices, must permit the automatic entry and discharge of flood water.
The Federal Emergency Management Agency (FEMA) requires in §44 CFR 60.3 (C5) that all new construction and substantial improvements of fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for entry and exit of flood waters. To meet these requirements, there must be a minimum of two openings having a total area not less than one square inch for every square foot of enclosed area subject to flooding. The bottom of all openings shall be no higher than one foot above grade. The openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of flood waters.
The International Building Code (IBC) (P. 259-1202.3.1) requires that openings for under floor ventilation comply with the opening requirements of the American Society of Civil Engineers (ASCE) 24 and the International Mechanical Code (IMC) (Table 401.6). Air exhaust and intake openings that terminate outdoors shall be protected with corrosion resistant screens, louvers or grills having intake openings of not less than one quarter inch and not greater than one half inch. Additionally, for foundation wall ventilation openings, they must be made rodent proof by covering the openings with perforated sheet metal plates not less than 0.07 inches thick, expanded metal plates not less than 0.047 inches thick, cast-iron grills or grating, extruded aluminum load bearing vents or with hardware cloth of 0.035 inches wire or heavier. The openings therein shall not exceed one quarter inch.
The International Residential Code (IRC) has established certain flood resistant construction (P54 §R327). In essence, the requirements for an enclosed area below design flood elevation used solely for parking of vehicles, building access or storage and must include flood openings which meet certain criteria. There must be a minimum of two openings providing a total net area of at least one square inch per one square foot of enclosed area. The bottom of each opening shall be one foot above the adjacent ground level. Any louvers, screens or other opening covers shall allow the automatic flow of flood waters into and out of the enclosed areas. Any openings installed in doors or windows shall meet these requirements.
The American Society of Civil Engineers (ASCE) §ASCE 24-98 is directed to flood resistant design and construction. In essence, it requires that foundation openings allow automatic entry and exit of flood waters during design flood conditions. These openings shall meet the following requirements. There shall be a minimum of two openings on different sides of each enclosed area. The total net area of all openings shall be at least one square inch for each one square foot of enclosed area. The bottom of each opening shall be no more than one foot above the adjacent ground level. Any louvers, screens or other opening covers shall not block or impede the automatic flow of flood waters into and out of the enclosed areas. Furthermore, the difference between the exterior and interior flood water levels shall not exceed one foot during periods of maximum rate of rise and maximum rate of fall of flood waters and at any other times during the design, or lesser, flood events.
Additionally, the Federal Insurance Administration has issued requirements for buildings located in special flood hazard areas under the National Flood Insurance Program (NFIP). All new construction and substantial improvements with fully enclosed areas below the lowest floor that are usable for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for entry and exit of flood waters. These requirements include a minimum of two openings having a total area of not less than one square inch for every square foot of enclosed area subject to flooding. The bottom of all openings shall be no higher than one foot above grade. The openings may be equipped with screens, louvers, valves or other coverings or devices provided that they permit the automatic entry and exit of flood waters. For buildings with attached garages, the openings are required in either the exterior walls of the garage or in the garage doors themselves. It is anticipated that a large amount of debris will be associated with flooding and the fact that the openings include some form of vermin (rodent) screen to meet the applicable building codes, there is a high probability that at least one opening may be obstructed during a flood. For this reason, openings are required in at least two different sides of the enclosed area, and must be incorporated in the calculations.